Microsoft announced some details of its Windows Phone performance in 2011, although the company omitted some key metrics – such as the total number of apps that have been downloaded, its daily run-rate, or the number of users of its Marketplace store.

According to the company, the average number of app downloads per user is 48, although it did not break-out the paid for/free split. It did state that 56 percent of WP7 users can have Marketplace purchases billed via their mobile operator, which it said offers an “increased opportunity to sell apps.”

There are “50,000+” apps in the catalogue, with entertainment (17 percent), tools & productivity (15 percent), books & reference (14 percent),  games (14 percent) and news & weather (7 percent) being the largest single categories.

However, there are some differences when it comes to apps downloaded by customers. Across both free and paid-for titles, the most popular categories are games, tools & productivity, and entertainment, with the remaining two top-spots taken by travel and music & video products.

In the paid for app category, games are by far the most popular (64 percent), ahead of tools & productivity (8 percent) and entertainment (8 percent) – no other category had more than 5 percent of the total. For free titles, while games are still the most popular (31 percent), tools & productivity (18 percent), entertainment (13 percent) and music and video (8 percent) also perform strongly.

Microsoft said that more than 80,000 developers are registered to build Windows Phone apps.